Electric device



Nov. 16, 1926.'

P. c. 'HE WITT ELECTRIC DEVICE Original Filed July 21. 1920 2 Sheets-Sheet l Nov. 16 1926.

P. C. HEWITT ELECTRIC DEVICE Original File July 21. 1920 2 Sheets-Sheet 2 w lm mror Hi6 A TTORAIEFS Patented Nov. 16, 1926.

UNITED STATES PATENT OFFICE.

PETER COOPER HEWITT, OF RINGWOOD MANOR, NEW JERSEY; THE FARMERS LOAN AND TRUST COMPANY. EXECUTOR 0E SAID PETER COOPER HEWITT, DECEASED, I ASSIGNOR TO COOPER HEWITT ELECTRIC COMPANY, OF HOBOKEN, NEW JERSEY, A

CORPORATION OF NEW JERSEY.

ELECTRIC DEVICE.

Application filed July 21., 1920, Serial No. 397,965. Renewed July 31, 1926,

The present invention relates to improvements in electrical devices wherein current is caused to flow in a circuit consisting of a true conductor and from one electrode to another through a space having conductivity of a different character and wherein such space is comprised in the device and the said current flow is affected for useful purposes at one or the other of said electrodes, or at both electrodes, or ata point or points between the electrodes, or at an electrode and a point between the electrodes, or at both electrodes and a point between the electrodes. The invention is useful in connection with devices containing rarefied gas or vapor and also having the highest exhaus tion and with devices having no ionization, as well as with devices of lower exhaustion and devices having ionization.

The object of my invention is to control the reaction attendant upon current flow at or between electrodes ,of an electric circuit for various useful purposes and to this end I provide a shield of material such as wire mesh or a number of such shields in operative relation to an electrode or the electrodes, or to a .point or points between the electrodes for affecting the said reactions.

A control electrode in the form of a perforate body, such as a screen or shield of material such as wire mesh, is useful for the purposes for which shields are used in evacuated rectifying devices and in'evacuated devices for producing varying currents from direct or alternating currents, and for purposes where it is desired to increase the voltage required to pass current through the device, and thereafter to decrease it, and is generally useful for the control and the modulation of the voltage required to pass current through the device and of the control of the electrical discharge conditions within the device for any purpose.

The discharge conditions of an electrode and reactions at and associated with an electrode, and also the conditions of conduction existing in the space between two electrodes may be modified by charges independently created and applied to the space between. the electrodes.

In many cases. when reactions in the space between two electrodes are modified so that the voltage required to pass equal current is increased, the current tends to concentrate and limit the area of the path of its flow so that when the reactions are modified, as by a screen or perforate plate interposed in the electric path between two electrodes and also by a screen through which the current would pass normally, when such screen is charged negatively, the current will tend to concentrate and pass at a single'spot instead of diffusing normally through a large area of the screen forming a shleld located in the current path.-

When the concentration of the current occurs, that is, when the current restricts its area and passes thru a shield or screen in such limited area, the reactions which govern its passage are not so easily nor to the same extent'controllable by charges independently applied as when the current is diifusedover the normal area.

It is often useful to modify the reactions within a device. for special purposes and particularly to increase the voltage required to pass current in order that this increase of voltage may be availed of as and in the manner of falling electromotive force as well as increasing electromotive force.

The object 'of my invention is to provide means whereby the reactions may be controlled and a shield or shields be used for controlling these reactions by charges applied through them without such concentration'of current as to impair the action, and to provide means whereby the action may be powerfully exerted.

I have discovered that where the substance of the shield is small compared to the area of the opening, that concentration does not take place with the same degree of electrical force applied; that is, in the case of a wire screen, as the size of the wire is decreased, the electrical force applied to the shield may be increased without promoting objectionable current concentration, and that diffused current may be caused to pass through one or more shields or screens located a small distance apart without concentration when the material forming them is sufiiciently fine.

' I have also found that there is less tend ency toward concentration of current when the shield is located in close proximity to the positive electrode, and that the discharge conditions of an evacuated device containing vapor of considerable density may be controlled within wide limits by means of a shield located in close proximity to the positive electrode. The current has a tendency to diffuse over a certain area of a positive electrode even in'vapors or gases of considerable density and there is a reaction in very close proximity to the surface of thEPOSltive electrode which is sensitive to electrical charges and also sensitive to the mesh of a shield in close' proximity to the positive. Such a shield tends to increase the voltage required to pass current through the device and this condition may be increased by the fineness and multiplicity of the openings 1n the shield. The natural increase brought about by the shield may be modified, and

when the shield is made positive to the negative to a lesser degree than the positive electrode is positive to the negative, the voltage required to pass current from the positive to the negative electrodes is lessened. The voltage is increased by the shields having a charge negative in some degree to the positive and increases as the shield is made more negative. It is decreased by the shields being positively charged from the negative; that is, when provided with a separate source of current and said source having a separate circuit to the negative. Additional controls may be provided by a plurality of shields or screens of very fine wire located in the path between two electrodes.

The wire for the shields or screens is preferably made of a high melting point material such as tungsten carbon or tantalum where powerful action is required, although lower melting point materials are serviceable, and those located in the vapor path between the electrodes may be as fine wire as is practically usable. The size of the mesh will probably be less than twenty to the inch, and with very fine wire may be less than one hundred to the inch. A practical screen may be made of wire, the material of which occupies substantially a relation of ten percent of the mesh; that is, the solid material covers about ten percent of the area and forms a depth of about ten percent of the opening. The screen at the positive will be substantially the same, but may not require the wire to be as fine.

The current has a tendency to diffuse over the surface of the positive. and this tendency assists dilfusion through the shield when the shield is in close proximity to positive. Moreover, there are reactions at and near the surface of the positive that makes it desirable to locate the shield close to the positive, when availing of these reactions and using them as means for or assisting control of the discharge or conduction condition of the device.

The shield, screen or control electrode is composed of wire gauze, the wire forming substantially ten percent of the mesh. When the wire is too large in diameter or forms too great a percent of the mesh, the current will tend to concentrate and pass through one and sometimes two or more meshes in concentrated form and the operation or control of the shields is modified and lessened very materially, and internal disturbances, electrical variation and resistance variation are produced.

In order to provide additional control with such a shield, it may be duplicated, or a multiplicity of them used, and they operate well at a distance apart substantially that of the mesh or greater distance, and greater separation may be used.

In the present invention the current path through a shield is very short in comparison to the distance from one side of the shield to the other, and the current does not concentrate and is not acted on by these shields in a concentrated state, but in a state of diffusion or by the boundaries of a number of openings. In the present case the unit surface acting on the current at right angles to its path is large. The current path is not acted on by any one gauze or screen forming the shield for a considerable distance parallel with and along the path of the current.

For the control of the current path one, two or more independent shields or control electrodes may be provided at different distances spaced along the path between the electrodes, and may consist of a multiplicity of parallel screens.

The solid material forming the shield or screen may be made of wire as fine as .0003 inches or less, and may be made of coarse wire or other material by observing the rule substantially relative to the spacing and depth of the openings.

An effective control is provided by two shields or control electrodes spaced along the path, one of which is in close proximity to the positive electrode, in a special form of device, having a gas or vapor pressure of considerable density, used as an electrical generator of high frequency currents from direct or alternating currents, by which frequencies are obtained equal and comparable to those obtained in devices having the lowest gas or vapor pressure of the order of the highest vacuum now obtainable, and a mercury vapor device having a glass container operating at comparatively high temperature, becomes serviceable for the genera- When the apparatus contains gases or vapors of considerable density, the internal temperature at the shields of the devlce 1s apt to be high when operating wlth currents of several kilowatts. It is therefore advantageous to use for the material forming the shield providing a control electrode or shield, a wire having a high melting point, and it is also advantageous that such material does not tend to exfoliate or fire off when in operation. High melting point materials are tungsten, tantalum, molybdenum, chromium,'iridium, platinum and carbon. Carbon, at a very high temperature, does not tend to act as a prohibitive negative as well as tungsten, although at lower temperature carbon has many valuable characteristics and is useful. At certain degrees of high vacuum certain materials mayact as substantially prohibitive negatives but inmost cases, and especially at lower vacuums when exposed in a current carrying media, they will pass more or less negative current with a very definite fixed maximum. For certain classes of apparatus it is desirable that they should pafs as little negative current as possible to obtain in order to enable the control of the apparatus with minimum control current; that is, obtain a negative charge at t the shield with minimum current passing.

Therefore the selection of material becomes a matter of a certain degree of importance for special apparatus, and will vary for special uses.

The gauzes are useful in various types of devices, for example, where one electrode is composed of mercury or other voltage material and operated at a considerable temperature, or where a solid material, such as tungsten, tantalum, platinum or carbon is employed. In the choice of materials, the chemical relation of the materials used are important as chemical reactions modify and impair the action and may shorten the life of the device. The physical reactions under the action of the current are also important in this connection.

This form of shield with devices of the highest exhaustion may be used to eliminate internally originated disturbances often occurring in such devices, and therefore shields of this character are of great value for affecting the control of devices for modulation and control of passing current for uniform effect, as more pronounced effects can he produced without producingthe attendant internal disturbances created that usually arise at or near the limit of practical operation of devices used for this purpose.

By way of example, I have illustrated my invention in the accompanying drawings as applied to a gas or a vapor electric tube, but it will be understood that the invention is applicable to any form of tube wherein a vapor or a gas is present or is absent or does Fig. 2 is a plan view of the foraminous material employed as a control member;

Fig. 3 is a diagram of a novel system of circuits and apparatus for producing high frequency currents as used in radio signalling; and

Fig. 4 is a diagram of a microphone and a key circuit applied to the system of Fig. 3 for transmitting speech or telegraph signals.

In the drawings, Fig. 1, 1 is a tube having a positive electrode, 2, and a negative electrode, 3, here shown as mercury being of volatile material, and having a suitable keep-alive circuit conventionallyv indicated at 4:, although a solid material, such as incandescent tungsten and keep-aliveor heating circuit may be employed, when desired. In practice, the current flow between the electrodes is obtained by connecting the electrodes 2 and 3 to a suitable source of current (not shown). In the path of the current flow and between the electrodes I mount a shield consisting of wire gauze, 5, or two or more wire gauzes, 5 and 5, if desired, supported by the container, the screens, when a plurality of them form the shield, being separated the required distance by rings of fsluitable material such as glass, 6, ground I have also found it advantageous to mount another shield, 7, which may consist of a plurality of parts, 7*, 7", at a point in the current path remote from the shield 5, to assist in the control action of the discharge conditions of the device.

lVhen it is desired to control the current flow through the device, an electrical connection from the screen 5, or the screens 5 and 5 to a suitable source of control, is provided by a lead wire 8; and by a leadwire, 9, when the screen 7 or the screens 7, 7 and 7 are used. A trap drain is shown at 10 for returning products of condensation from the positive chamber to the cathode, when a condensable gas, such as mercury, is used as the negative electrode.

In Fig. 3, the tube 1 of Fig. 1 is shown as employed in a radio signalling system and connected to a current supply circuit consisting of a source of current either direct or alternating current, 11, resistance, 12, and inductance 13, 13. The tube 1 is shunted by a circuit containing inductance 14, and capacity here shown as condenser 15. In inductive relation to the inductance 14 is an inductance 16 in an antenna comprising aerial, 17, tuning inductance, 18, and ground Wire, 19.

The control apparatus for the outfit above described comprises an inductance, 20, inductively related to the induc'tances 14 and 16, and connected to the leads 8 and 9 of the screen devices 6 and 7, respectively, through a condenser, 21, and causing theoscillations generated in the inductance 16 to react upon the conducting path of the tube 1. The screens, shields, or control electrodes 6 and 7 are maintained at proper potentials by the batteries 22 and 23, respectively. The potentials of the batteries contributing as means of control. An impedance device, 24, is connected across the leads 8 and 9 and in series with the battery 22, to exclude high frequency currents from this path.

When the outfit is started into operation in a manner now well understood in the art, by closing the current supply,.the oscillations created by current passed by the device in the antenna are caused to react through the coil 20 and its circuit through the control electrodes 6 and 7 on the current path of the tube 1, controlling the current passed by the tube 1. To vary the operation for radio telephony, a switch 25, (Fig. 4) is thrown to the left connecting a microphone, 26, in' circuit with a battery, 27, and a coil, 28, inductively related to coil 24. Throwing the switch, 25, to the right cuts the microphone out of circuit and connects a key and buzzer conventionally shown at 29 into the sending circuit for radio telegraphy.

I claim as my invention:

1. An electric device comprising a container, a positive electrode and negative electrode of vaporizable material therein, and a shield between said electrodes, and in operative relation to the positive electrode, said shield consisting of a screen wherein the solid portion is uniformly distributed, being not more than 12% of the surface.

2. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a shield being formed of solid material being substantially 10% of the area and the mesh being not more than 1/20th of an inch located between the electrodes and in operative relation to the positive electrode for preventing current concentration.

3. An electric device comprising a container, a positive electrode and anegative electrode of vaporizable material therein, and a shield of spaced members between said electrodes and in operative relation to the positive electrode, and an electric connection to said shield for controlling the discharge conditions of the device.

4. In an electric device, a container, a positive electrode and an active negative electrode therein, a control electrode in operative relation to the positive electrode for controlling the discharge conditions adjacent to the surface of said positive electrode of said device, means for applying a potential to said control electrode, and means for varying said potential.

5. In an electric device, a container, a

positive electrode therein, an active negative electrode comprising vaporizable material therein, a control electrode between said electrodes and adjacent to the positive electrode and substantially coextensive with the active surface of the said positive electrode for controlling the discharge conditions of the device.

6. In an electric device, a container, a positive electrode therein, an active negative electrode comprising vaporizable material therein, a control electrode of spaced members adjacent to the positive electrode-and substantially coextensive with the active surface of the said positive electrode for controlling the discharge conditions of the device.

7. In an electric device, a container, a positive electrode and a negative electrode comprising vaporizable material, a control electrode in operative relation to the positive electrode for controlling the discharge conditions adjacent to the surface of the said positive electrode ofsaid device, means for applylng a charge to said control electrode, and means for varying said charge.

' 8. In an electric device, a container, a positive electrode and a negative electrode comprising vaporizable material, a control electrode in operative relation to the current path adjacent to said positive electrode for controlling the discharge conditions adjacent to the surface of the said positive electrode of said device, means for applying a charge to said control electrode, and means for varying said charge.

9. In an electric device, comprising a container, a positive electrode therein, a negative electrode of vaporizable material therein, a shield of spaced members adjacent to the positive electrode, and an electric connection to said shield for controlling the discharge conditions adjacent the surface of the said positive electrode.

10. In an electric device, a container, a positive electrode therein, a negative electrode of vaporizable material therein, a shield of spaced members adjacent to the positive elec trode, means for applying a charge to said shield and means for varying said charge to control the discharge conditions adjacent the surface of the said positive electrode.

-11. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, a shield of spaced members adjacent to the positive electrode and through which the discharge from the'said electrode passes and an electric connection to said shield for controlling the discharge conditions of the dev1ce.

12. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material thereln, a shield of spaced members adjacent to the positive electrode and through which the discharge from the said electrode passes, and means for applying an electric charge to said shield for controlling the discharge conditions of the device.

13. An electric device comprising a container, a positive electrode and a negat ve electrode of vaporizable material thereln, a shield of spaced members adjacent to the positive electrode and through which the discharge from the said electrode passes, and means for applying an electric charge to said shield for controlling the discharge conditions of the device and means for varying the said charge.

14. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a screen in the current path between said electrodes and in operative relation to the positive electrode for controlling the conductivity of the current path and avoiding deleteriously modifying its character.

15. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a plurality of screens in the current path between said electrodes, one of said screens being in operative relation to the positive electrode for controlling the conductivity of the current path and avoiding deleteriously modifying its character.

16. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a-plurality of shields in the current path between the electrodes, one of said shields being in operative relation to the positive electrode for controlling the conductivity of said current path for avoiding current concentration, in which the size of the openings is less than to the size of the solid material, and means for applying electric potentials to the shields.

17. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a 'shield between the electrodes and in operative relation to the positive electrode for preventing current concentration, and means for applying an electric charge to said shield.

18. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a shield in operative relation to the positive electrode and composed of openings of uniform size, said openings being less than a twentieth of an inch, and in depth not more than ten per cent of the opening, means for applying a steady potential to the shield, and means for varying the potential.

19. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a shield in the current path between the electrodes and in operative relation'to the positive electrode in which the area of the solid portion of the shield is less than the area of the opening, and the vapor or gas density.

20. An electric device comprising a. container, a positive electrode and a negative electrode of vaporizable material therein, and a shield in the current path between the electrodes and in operative relation to the positive electrode in which the area of the solid portion is less than the area of the openings and means for applying electric currents to the shield.

21. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein,

and a shield in the current path between the electrodes and in operative relation to the positive electrode in which the area of the solid portion is less than the area ofthe openings, and means for applying a definite potential to the shield.

22. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a shield in the current path between the electrodes and in operative relation to the positive electrode in which the area of the solid portion is less than the area of the openings, means for applying a definite potential to the shield, and means for applying variations of potential to the shield.

23. An electric device comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a shield in the current path between the electrodes and in operative relation to the positive electrode in which the area of the solid portion is less than the area of the openings, means for applying a definite potential to the shield, and means for varying the effects of the definite potential.

24. An electric device for generating alternating currents, comprising a container, a positive electrode and a negative electrode of vaporizable material therein, and a shield in operative relation to the positive electrode and separated from it less than one eighth of an inch and consisting of wire gauze wherein the solid material forms substantially ten percent of the mesh.

25. In an electric apparatus, the combination of a source of current supply a device connected thereto and comprising a container having a positive electrode and a continuously operating negative electrode therein, a control electrode in operative relation to the positive electrode for controlling the discharge conditions adjacent to the surface of said positive electrode of said device,

means for applying a potential to said control electrode, and means for varying said potential.

26. In an electric apparatus, the combination of a source of alternating current sup ply, a device connected thereto and comprising a container having a posltlve electrode and a continuously operating negative electrode therein, a control electrode 1n operative relation to the positive electrode for controlling the discharge conditions ad acent to the Surface of said positive electrode of said device means for applying a potential to said control electrode, and means for varying said potential.

27. In an apparatus for producing alternating currents, the combination of a source of current supply, a device connected thereto and comprising an exhausted container having a positive electrode and a negative electrode of vaporizable material therein, and a shield in the current path between the electrodes and in operative relation to the positive electrode, preventing current concentration when afiected by varying potential.

28. In an apparatus for reproducing alternating currents, the combination of a source of current supply, a device connected there to and comprising an exhausted container having a positive electrode and a negative electrode of vaporizable material therein, a shield in operative relation to the positive electrode, said shield being less than threesixteenths'of an inch from the positive electrode and consisting of a wire gauze of which the solid material forms substantially ten percent of the mesh, means for applying a definite potential to the shield, means for applying'variations of potential to the shield, and an output circuit electrically connected with the device and an alternating current energy consuming means associated with the said output circuit.

29. In an apparatus for reproducing alternating currents, the combination of a source of current supply, a device connected there-.

to. and comprismg an exhausted container having a positive electrode and a negative electrode comprising vaporizable material therein, a shield in operative relation to the positive electrode, said shield being less than three-sixteenths of an inch from the positive electrode and consisting of a Wire gauze of which the solid material forms substantially ten percent of the mesh, means for applying a definite potential to the shield, means for varying the definite potential, and an output circuit electrically connected with the device and an alternating current energy consuming means associated with the said output circuit.

30. In an apparatus for producing alternating currents, the combination of a source of current supply, a device connected thereto and comprising an exhausted container having a positive electrode and a negative electrode comprising vaporizable material therein, a plurality of shields of wire gauze in close proximity to each other and one of which is in operative relation to the positive electrode, means for applying a definite 'potential to the shields, means for applying variations of potential to the shields, means for varying the definite potential, and an output circuit electrically connected with the device, and an alternating current energy consuming means associated with the said output circuit.

In testimony whereof I hereto aflix my signature.

PETER COOPER HEWITT. 

